<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>显示年龄</title>
		<script type="text/javascript">
			var age = prompt('您今年几岁了?');
			alert('您今年' + age + '岁了！');
			var s= null;
			console.log(s + 'hello')
			console.log(typeof s);	//object
			console.log(Number('12.21143px'))
		</script>
	</head>
	<body>
	</body>
</html>
